Lenovo — Lenovo mobile A6000 low standerd

I purchased mobile lenovo A6000 from Emerates hypher market I cad shopping center.It worked almost eight months.Than out of service.Software installation aborted.Showing only lenovo logo.I gave it to the same market for service on 07 Dec, 2016.As I received back it had same problem.Again on 25 of Dec 2016 I gave them for service.But until now they cannot fix it and no any cooperation from market employees, rude to the customer as well.If a product is not working in warranty and continously going to send for the service.Being as a customer how I can trust the same unit that it will work properly in future.
I hope you will understand my concern and you will provide me proper and quick feedback.